Okay I have done several month long road trips. I love this stuff. Really depends where you are starting from and what you are into. These are some great drives that I have done, they do take some research but, they are well worth it!
The Pacific Coast Highway: Okay this is a great stretch of road, you can start at the begining in WA or jump on somewhere in between. First time I did OR and CA. There is so much to do all the way down and cheap things! There is a ton of outdoor stuff and the most beautiful places that you will ever see! I really like the drive through OR and the north of CA wow the coast is great. This is a very slow driving road, good for a long trip. There is also a lot of wacky tourist things to do made for good fun and pictures. Good places to camp and very cheap!!!!! Be wise contact the local chamber of commerce and ask for a visitors packet they have coupons, also tell them you need a cheap place to stay or sleep they will help. They will also send maps and info on the area FREE services great for all trips! There is just sooo much to see that I am going to just list some sites here:
www.us-101.com
www.byways.org
www.experiencewashington.com
www.traveloregon.com
www.travelportland.com
www.covisitors.com
www.gonorthwest.com
www.visitlanecounty.org
Another really great trip, is Route 66. People will tell you that you cannot drive much of it, so not true. I have done this trip over and over. I was 25 the first time I started doing it and I still love it! Okay if you want to do this it does take some research and some good maps. With that said it goes across IL, MO, KS, OK, TX, AZ, NM,and CA. This is a wonderful trip you get to see alot of different things! You can do this for cheap! Food is cheap and good (got to love diner food), the locals are all nice (they are proud of their old highway) there is a ton of touristy stuff for cheap to do (Seilgman, Vicitorville, Oatman, ect...) there are some great parks which are free or cheap. You get to see a lot of America and the scernery is great. You have hills, flatlands, moutains and deserts and it ends at the ocean. They have some really cool places to stay like the Wigwams and they are cheap! They also have some really nice campgrounds and they are also cheap! Motels that are nice will run about $30-$40. We found all kinds of crazy little musuems, like the barb wire musuem, the sing musuem and so on. There is the Grand Caynyon the Petrified Forest, the Metor Crater, Bandaro Cave and more. Take the time to research this, you can see a lot of America on a budget! Here are some sites to help:
www.historic66.com -- This is the best site around the directions are very good. What I did is I looked up the local Chamber of Commerce website for each town on the map. Some are so small they do not have one, but a lot did. I emailed them and that is how I found some great spots!
www.national66.com
www.oklahomaroute66.com
www.rt66nm.org
www.missouri66.org
www.azrt66.com
www.route66usa.com
www.califrt66museum.org
www.il66assoc.org
Okay well a few years ago we drove from Texas to Florida basically drove the coast. Went through NO (do not sleep in your car there). Gulf Port, Destin Ect. There are several ways to do this trip because depending on what you are looking for certain cities might be better than others. Look at the map there are some major and back highways you can take, I really liked seeing the plantations and going on the swamp tours in LA the good part was we ended up at the beach. TX was pretty cool, I really would have just done LA, MI and FL myself. We ended that trip on Sanibel. Too expensive now but, you can stay in Fort Meyrs for cheap!
You might also think about driving around GA. Athens, Rome, Atlanta (again no sleep in the car here), Savannah are all great cities. If you visit the GA website they have some great driving tours and they will send you out the maps for free. I really like GA because there is a lot to see. Savannah is my favorite city! Good music in Rome. Here is a site to help:
www.georgia.org
You might also want to check out this site:
http://www.byways.org/
good site they will send you free maps, has all of the great driving tours of America. You can look at them online. I find some great places with this site.
Here are some other sites I use when planning a road trip, I hope they help:
http://www.roadsideamerica.com/
This site is great has crazy tourist stuff to do. A lot is free of very cheap crazy, and different things!
http://www.roadfood.com/
Got to have good food on the road is very helpful!
http://www.gasbuddy.com/
Helps budget for gas
http://www.gaspricewatch.com/new/
another gas friend
http://www.frommers.com/
Good place for maps and ideas
Okay here are a few other tips for the road trip. Coupons are your friend, trust me! Pick up all the books, go to all the sites, request all free visitors stuff you can. They help on admission, food and lodging. Do your research, know where you want to go, what you want to do, you can find prices online, this helps you budget and keeps you on course. Take a cooler and eat lunch at a pinic area. Saves massive cash, take snacks, breakfast whatever. Sometimes we eat out only once if all. Check out hostels...get the movie out of your head. The US does have some good hostels, takes research to find. Some have private rooms, others just dorms. I have stayed at a few and all have been great. You can get a bed for as a low as $8 a night and there is a kitchen shower and common room. Good option for shelter! Don't buy things, do you really need the post card ect... You won't remember it years to come.
Last thing, please re-think the car thing, I say this because I am a single female that does traveling, by myself and with others. You can find cheap places to stay! If you want to sleep in the car stay at a cheap campground, way safer than sleeping at a visitors center or the side of the road. With a little thought and some research you can do it! Hope this helps have a great trip!